1. Field of the Invention
The invention is a method of chemical analysis for detecting and reporting contraband such as illicit and illegal drugs, explosives, toxic chemicals, decaying animal and vegetable matter, and concealed human beings located in confined spaces of shipping containers and other cargo containers and secure spaces. The chemical analyses take place periodically while the containers are in transit from the time that the containers are stuffed and sealed, to the time when the containers move through inspection chokepoints, through the shipping time of the containers, and to the time that the containers are inspected at national border crossing points. During the transit time concentrations of chemical vapors of the materials to be detected, i.e., the target chemicals, increase by diffusing out of packaging into and throughout the container. The periodic chemical analyses are added together which has the effect of emphasizing responses of the analysis to chemicals that are increasing in concentration or that have reached a steady-state concentration while averaging out or de-emphasizing responses to chemicals that fluctuate in concentration. In addition, signal processing enhancement of spectra, for example, spectral deconvolution, can be employed during the extensive analysis time available while the containers are in transit. Total analysis time ranges from a few hours to several days.
2. Description of Related Art
At the present time, there are no methods or procedures for monitoring the contents of shipping containers, storage containers or other cargo containers by having a detector within the container. When such a container arrives at its destination, a statistical number of containers are randomly tested by sampling the exhaust vent of the container for a selected type of target chemical. The test does not include all types of potential contaminants. Further, due to time and cost constraints, the sampling time is relatively short and may not be a representative sample of the contents of the container.
Ion mobility spectrometry (IMS) devices for detection of contraband, drugs and explosives, are commonly used by inspection personnel at security chokepoints in airports, seaports, and border crossings throughout the world. IMS devices for detection of chemical warfare agents are used worldwide by military, law enforcement, and security personnel to detect and prevent exposure to lethal and incapacitating chemicals. However, current applications of IMS detection devices, or other analytical chemical instruments, require high speed of response to prevent bottlenecks at security chokepoints and to detect toxic chemicals before the chemicals are ingested by people in sufficient quantities to be physiologically dangerous. In every previous method and application of analytical chemical instrumentation, analyses of atmospheres for contraband or dangerous materials, minimization of response time has been emphasized. Many of the detection systems require human operators who acquire samples, introduce samples into the detector, and monitor detector results.
There are no known methods or applications of analytical chemical detection instrumentation, for example IMS devices, for accumulation and addition of chemical detection data inside of shipping containers while the containers are in transit for the purpose of detecting and reporting decaying animal and vegetable matter. There are no known methods or applications of analytical chemical detection instrumentation, for example IMS devices, for accumulation and addition of chemical detection data inside of shipping containers while the containers are in transit for the purpose of detecting body effluvia from concealed human beings although it is common knowledge in the analytical chemistry field that human effluvia such as ammonia, carbon dioxide, sulfides, volatile organic acids, amines and diamines are readily detectable by IMS.
IMS technology and devices based on IMS technology have been developed for detection of drugs and explosives. One example of detection systems for drugs and explosives is the detectors at airport security check-in locations. The operator of one of these devices must rub a swab over a piece of luggage and then place the swab in an instrument to determine whether there are certain chemicals on the bag, i.e., chemicals that have been transferred to the bag due to previous handling of the contraband. Emphasis is on speed of response but this process requires a few minutes and operator intervention and is impractical for use on every passenger passing through an airport. Similar instruments have been proposed for use by Customs inspectors who attach them to vents of shipping container, a process requiring several tens of minutes to an hour making it impractical to examine every container passing through seaports. These detection instruments are designed to detect either drugs or explosives but not both at the same time—the instruments must be reprogrammed from detection of one form of contraband to detection of another form of contraband.
There are millions of shipping containers and cargo carriers in use in the world and many more millions of container and carrier uses per year. Inspection of cargo containers and carriers is time consuming and results in delays in timely movement of containers across national border crossing, through seaports, and through airports. A detailed inspection of a single cargo container for contraband substances can take hours to accomplish. Speeding of the inspection capability is a prime interest of governments around the world to provide timely and efficient interdiction. The method described in the present patent application will facilitate the inspection process by indications of containers that are likely to contain contraband or to indicate containers that need not be inspected.
The present invention pertains to a method of chemical analysis for detecting and reporting contraband and not the detection device. A small, unobtrusive, low power consumption device is pertinent from a practical point of view because of limited space available in packed shipping containers and because of the need to perform chemical analyses over periods of several hours to several days. The present invention is for chemical analysis to take place while cargo containers are in transit from the time that the containers are stuffed, to the time when the containers move through inspection chokepoints, through the shipping time of the containers, and on to the time that the containers are inspected at national border crossing points. This is in contrast to requirements for rapid response of detection instrumentation that is currently employed for inspecting cargo containers at transportation chokepoints. The present invention relies on the fact that the total time available for employing the method of analysis ranges from a few hours to several days.
In Publication US 2005/0022581, Sunshine discloses a chemical sensing system having an interrogation unit to wirelessly transmit an interrogation signal and to wirelessly receive a response. Various sensors are disclosed, none of which are IMS. Also, a sample is introduced into a container, the sample having a relationship with an analyte in the container which is detected by the sensor.
The use of a gas chromatograph—IMS device to analyze high volume vapor samples from cargo containers is reported by La Fontaine in the 9th International Conference on Ion Mobility Spectrometry, Aug. 13-16, 2000.
Thus, there is a need for a method which can detect the presence of target chemicals in confined spaces such as cargo shipping containers as the containers are in transit and concentrations of the target materials accumulate over a period of time. There is a further need to move the shipping containers rapidly through the transportation choke points.